The common theme of this research is the exploitation of biological rhythms in clinical medicine (i.e., applied chronobiology). Three principal applications have been investigated: 1. Whether there are systematic circadian variations in the efficacy of thiazine diuretics in man. 2. Whether specific abnormalities of circadian rhythms occur in blood or urinary variables in patients with Bartter's syndrome. 3. Continuing investigation of circadian and menstrual rhythms of female breast surface temperature as a dynamic record of cyclic function. This is a preliminary to testing (epidemiologically) high- and low-risk groups for evidence of pre-cancer.